The November 21, 2017 ruling came in a December 2016 lawsuit brought by Judicial Watch on behalf of California taxpayer Cynthia Cerletti. The lawsuit alleges Sheriff Hennessy's restrictions on communications with ICE conflict with federal immigration law and are therefore invalid.

San Francisco's sanctuary policy received national attention on July 1, 2015, when Kathryn Steinle was gunned down at one the city's most popular tourist spots, allegedly by Jose Ines Garcia Zarate (formerly known as Juan Francisco Lopez-Sanchez), an illegal alien who had been released from the San Francisco Sheriff's Department despite a request from ICE that he be detained for possible deportation. On Thursday, November 30, a San Francisco jury acquitted Zarate of murder.

Sheriff Hennessy's refusal to share basic information about the release of deportable criminal aliens in her custody – the date, time, and place of their scheduled release – plainly frustrates Congress' clear purpose in enacting section 1226(c). By refusing to share release information, Sheriff Hennessy allows deportable criminal aliens in her custody – aliens Congress plainly intended to be detained upon release from the custody of [law enforcement agencies] such as SFSD – to escape federal immigration officials' grasp. Her restrictions enable aliens who have committed aggravated felonies or other crimes deemed sufficiently serious by Congress to warrant detaining them and denying them bond or conditional parole to remain at large pending removal. Not only might such persons pose a further danger to the community – which was one of Congress' main concerns – but federal immigration officials must spend additional time and resources and assume unnecessary risk to themselves, the aliens, and others locating and apprehending them.

In rejecting the attempt to end the lawsuit, presiding Superior Court Judge Harold Kahn wrote there is "sufficient support at this stage of the case for Ms. Cerletti's allegation that the Sheriff's policy prohibiting or restricting release information about suspected priority aliens stands as an obstacle to the accomplishment of Congress' asserted purpose of enabling federal immigration officials to gain access to inmates who may have violated federal immigration laws." The lawsuit may now proceed to discovery.